Transcript Hearing_6.ppt

Hearing
Conservation Training
For At Risk Workers
Is There a Problem?



More than 30 million Americans are
exposed to hazardous sound levels on
a regular basis
10 million have suffered irreversible
noise induced hearing loss
Rate of hearing loss is increasing in the
U.S.
Good Hearing is Important

Construction sites
are dangerous
– your ears help you
detect hazards
• back up alarms
• vehicle traffic
• changes in
equipment noise
• verbal warnings from
other workers
Good hearing is important

Commercial Motor
Vehicle Operators &
Equipment
operators
–
–
–
–
–
–
dump trucks
cement trucks
vacuum trucks
paint trucks
backhoes
crane operators

Need to hear
– the vehicle &
surroundings while
driving
• communication by
radio & with workers
on sites
• detection of external
warning signals
• detection of
mechanical signals
• performance of
routine driving tasks
Good hearing is important

Commercial motor vehicle operators
with a CDL
– FHWA requires CDL holders to maintain
good hearing
• meet physical qualifications (FHWA)
– hearing loss in better ear no more than…
– average of 40 dB at 500, 1000, 2000 Hz with
or without hearing aid
Group Exchange

What is your favorite
sound?
– Could you hear your
favorite sound if you
had a hearing loss?

What sound on a
construction site
alerts you to
danger?
The ear is a delicate tool
Inner ear

Cochlea
– inside are nerve cells
called hair cells
• fragile

Continuous noise
– above 90 dBA
• as bad for hair cells
as continuous foot
traffic is to grass
What is Noise?

Noise is a physical energy that moves
through the air like ripples in a pond
– noise is directional
– noise will bounce off walls and other
objects
Two Components of Noise

Frequency
– perceived as “pitch”
– measured in hertz
(Hz)
– human ear most
sensitive in the 1,000
to 4,000 range
• speech frequency
ranges

Intensity
– perceived as
“loudness”
– measured in
decibels (dB)
– “A” scale minics the
human ear
• used for noise
surveys
How is noise measured?

Sound level meter
– instant noise readings
– generally A scale used
• mimics the human ear

Noise dosimeter
– measure a workers
noise exposure over a
shift
• daily dose of noise
– very accurate
Units of Measurement for Noise

Decibel dB

– little increases on the
decibel scale make a
big difference
• a 6 decibel increase in
noise is equal to doubling
the intensity or loudness
of the noise

Earplugs needed
• noise above 90 dBA
• recommended at 85 dBA
Examples at Home
• 20 dBA whispered
voice
• 40 dBA refrigerator
humming
• 60 dBA normal
conversation
• 74 dBA average TV
• 80 dBA blender
• 95 dBA lawn mower
• 110 dBA leafblower
• 115 dBA chainsaw
Noisy Hobbies

Guns

• large caliber short
barrel = 130 dBA
• shotguns & high
powered rifles = 140
dBA

riding motorcycles
•
•
•
•

snowmobiles
• 120 dBA
electric drill = 95 dBA
power saw = 110 dBA
air tools = 120 dBA
belt sander = 93 dBA
walkman headsets
• 90 dBA
• 90 dBA

Woodworking

rock concerts
• 140 dBA
Noise in your workplace
• pneumatic hand held
grinder 101 dBA
• air hammer 105 - 130
dBA
• pavement breaker
114 dBA
• power actuated nail
gun 94 - 117 dBA
• portable saw 105
dBA
• air wrench 107 dBA
• Hydraulic post driver
123 dBA
• arc welder 116 dBA
• traffic line grinder 91101 dBA
• loader - 88 - 91 dBA
• paver 86 - 96 dBA
• snowplow 87 - 97
dBA
• 10 yard truck 76 - 85
dBA
• vactor truck during
operation 91 - 106
dBA
Communication in noisy
environments

Hard to hear someone talking in noisy
environments
– the speaker needs to be louder than
background noise

CB’s & radios or cell phones will need to
be turned up
– if you have a hearing loss, it will be harder
to distinguish speech in this environment
How do you know you are
exposed to damaging noise

Feel the need to shout in order to be
heard 3 feet away
– sound levels probably approaching 85 dBA

If immediately after a period of high
noise exposure
– ringing, buzzing or whistling is noticed

Equipment is tagged or marked as
noise hazardous
How much noise can you be
exposed to?

OSHA rules
– 90 dBA averaged over an 8 hr shift
• requires the use of PPE or other controls to
reduce your exposure
– earplugs should be used whenever noise is 90 dB +
– 85 dBA averaged over an 8 hr shift
• requires your employer to enroll you in a
hearing conservation program
– training
– hearing tests & follow up
What is a TWA?


This is a daily “dose” of noise not a
single exposure to a noisy piece of
equipment
Your daily dose of noise (TWA) is a
function of:
– how loud the equipment is (intensity)
– how close you are to the noise
– how long you are exposed to the noise
5 main causes of hearing loss





Heredity
Infections
Acustic trauma
Prescription drugs
Presbycusis
Types of Hearing Loss

2 Basic Types of Hearing Loss
– Conductive
• A hearing problem involving the outer ear or
middle ear
– Sensorinural
• A hearing problem involving the inner ear

Mixed hearing loss
– A problem involving the outer, middle and
inner ear is a mixed hearing loss
Conductive hearing loss

Causes
 middle ear infections,
 collection of fluid in the middle ear
 blockage of the outer ear (by wax),
 damage to the eardrum by infection or trauma,
 otosclerosis, a condition in which the ossicles of the
middle ear become immobile because of growth of
the surrounding bone,
 rarely, rheumatoid arthritis affects the joints between
the ossicles.
Sensorineural hearing loss

Sensorineural hearing loss
 age-related hearing loss,
 acoustic trauma (loud noise, etc.) to the hair cells,
 viral infections of the inner ear
 certain drugs, such as aspirin, quinine and some
antibiotics, affect the hair cells,
 Meniere’s disease
 acoustic neuroma (a benign – non-cancerous –
tumor of the auditory nerve),
 meningitis (infection of the coverings of the brain),
 encephalitis (infection in the brain),
Tinnitus

Hearing loss may not be silent ….
– Persistent (often or all the time)
• Ringing, roaring, clicking or hissing sound
– 12 million Americans have Tinnitus
– should be evaluated by a Dr.
– smoking, alcohol & loud noise can make it
worse
– use earplugs whenever exposed to noise
In addition to hearing loss….

Exposure to noise can….
– Cause increased fatigue
– headaches
– increase the heart rate and blood pressure
– cause muscles to become tense
– cause indigestion
– can lead to impaired balance
– make it more difficult to hear audible
warning devices
Noise induced hearing loss

Entirely preventable
– “People would pay more attention to
hearing loss if it caused a lot of physical
pain”
How do you know how well you
hear - Hearing Testing

Required annually for those employees
enrolled in a hearing conservation
program
– identifies anyone with a change in hearing
• this is just a “screening test” and should not be
used to diagnose the type or extent of hearing
loss
– testing helps determine the effectiveness of
an employers hearing conservation
program
Audiograms
Computer generated “tape”
showing normal hearing
Computer generated graph
of normal hearing
Degrees of Hearing Loss

Normal
10 - 25 dB

Mild
30 - 45 dB

Moderate 50 - 65 dB

Severe
70 - 85 dB

Profound
90 dB
Example of hearing loss

Have you had a
STS?
– an average shift of
greater than or equal
to 10 dB at 2000,
3000, 4000 Hz
– calculated by
• comparing your
baseline test with
your present hearing
level
Did you do poorly on your last
hearing test?

The following can result in a bad test
result
– exposure to noise without hearing
protection before the test
– failure to follow the technicians instructions
– fatigue
– substance abuse
– Tinnitus
– pseudohypacusis (faking it)
How to Prevent Further Hearing
Loss at Work





Identify noise hazardous equipment
Put distance between you and the noise
source
Limit the amount of time you are
exposed
Modify the noise source so it is quieter
Use hearing protection when around
loud noise
PREVENTION:Identify noise
hazardous equipment

Measure noise sources at your job site to
determine what poses a risk to hearing
– include any equipment that produces 85 dB or
greater in your inventory
PREVENTION:Identify noise
hazardous equipment

Label or ID any
equipment that
exposes the
operator to 90 dBA
or more

always use hearing
protection when
working with labeled
equipment
PREVENTION: Put distance
between you and the noise

Walk away from the
noise source
– Doubling your
distance from the
sound source
decreases intensity
by 6 dB
• a 50% reduction in
intensity!

Move the source
away from people

Move noise sources
away from
– reflective surfaces
(concrete or brick
walls)
• estimated to reduce
levels by 3 dB
– corners
• estimated to reduce
levels by 6 dB
PREVENTION: Limit the
amount of time you are exposed



Schedule noise activities for fewest
workers needed for the job
Take breaks away from the noise
hazardous area
Limit the amount of time employees are
exposed to noise
PREVENTION: Modify the
noise source

Noise Control - Maintain Equipment
– Reasons machines get noisier over time
•
•
•
•
•
•
•
worn components
loose parts
poor lubrication
imbalances
obstructed airways
blunt cutting surfaces
damaged/removed silencing equipment
PREVENTION: Modify the
noise source

Control types - barriers or pads
– Prevents sound from travelling on a path
– Portable welding-type noise barrier
– Cover metal surfaces with a coating, cloth, pad or
blanket to reduce impact noise
– Clamping material while cutting with a circular saw
PREVENTION: Modify the
noise source

Enclosures on equipment cabs
– Keep driver from equipment noise
• open bulldozer is on average 6 dB higher than a
closed bulldozer
• Glassed in cranes are on average 10 dB lower
than non-enclosed
Keep your windows
rolled up!!
PREVENTION: Modify the
noise source

Purchasing & Contracting
– Purchase quieter equipment
• specify in contracts for new equipment that low
noise & vibration levels are desired
– Specify in contracts with prime or
subcontractors that low noise practices will
be incorporated into the job when feasible
PREVENTION: Modify the
noise source

Retrofit old Equipment
– Modify existing equipment
• you may need the assistance of a trained
mechanic or a noise engineer
– Purchase noise reducing components like
mufflers & silencers
– Install quieter components
• Jackhammer/chipper: rubber chucks, seal lines
PREVENTION: Use hearing
protection

It is common for less
than 50% of the
employees who
should be wearing
hearing protection
actually wear them
in most industries

If you have a
hearing impairment
it is critical you use
them whenever you
are exposed to
noise
– both on and off the
job site!
HPD used - earplugs

Earplugs
– pre formed (latex)
– hand formed
(polyurethane or
PVC)
HPD used - canal caps & ear
muffs

Canal Caps

Ear Muffs
Noise Reduction Rating



All hearing protection devices have a
NRR assigned
NRR’s do not accurately reflect
attenuation in the real world
Field testing indicates……
– NRR is approximately half of what is listed
for earplugs
– NRR is approximately 75% of what is listed
for earmuffs
NRR’s - Good Rule of Thumb


Take the NRR on
the package and
divide the number
by 2
for example……
– earplug with NRR of
30 dB most likely has
a working
attenuation of 15 dB

Goal
– select protection that
will reduce your
exposure below 85
dBA

Backhoe = 93 dBA
– earplug with a NRR
of 20 so attenuation
is about 10
• 93 - 10 = 83 dBA
NRR the myth

Bigger is not necessary better
– Large NRR may not be appropriate if
• noise levels are in the high 80 dB to low 90 dB
range
– what is needed is not an NRR of 30 dB but a wellfitted and comfortable device that can provide an
actual delivered 10 or 15 dB of noise reduction
• if the need to speak and be understood is
needed in the noise environment
– flat and moderate attenuation passive devices can
be used
Flat Attenuating Devices

Good for
– noise exposures
averaging 85 - 95
dBA as a TWA
– environments were
the spoken word
needs to be heard
– those employees
with a hearing
impairment
EAR UltraTech
Bilsom NST 817
Hearing aids are not hearing
protection


Hearing aids do not block out enough
sound for most occupational exposures
to noise
When hearing aid users are exposed to
harmful levels of noise they should
– remove their hearing aids and use hearing
protection or
– turn off their hearing aids and put ear muffs
on over them
The bottom line…...

Your ears are a delicate tool - if your
working with broken equipment you
need to address your exposure by…
• getting further evaluation from an audiologist;
otogaryngologist; physician
• choosing hearing protection that is right for you
• asking for your employers help in evaluating
your working environment and making changes
to reduce your exposure
Wrap Up

Want more information…..
– Stay tuned & watch the video that will
provide more information for those with a
hearing impairment
IDENTIFY
EQUIPMENT
MOVE
AWAY
LIMIT
EXPOSURE
TIME
MODIFY
THE
SOURCE
PROTECT
YOUR EARS